Function bitScanForward

src/Core/src/Numerics.cpp:14–37

Finds the first bit set in a 32-bits numeral and returns its index, or -1 if no bit is set.

{
    // Finds the first bit set in a 32-bits numeral and returns its index, or -1 if no bit is set.
    int32_t bitScanForward(uint32_t source)
    {
#if defined(_MSC_VER) && (_MSC_VER >= 1400) // Visual Studio 2005
        unsigned long i;
        uint8_t success = _BitScanForward(&i, source);
        return success != 0 ? i : -1;
#elif defined(__GNUC__)
        auto result = __builtin_ffs(source);
        return result - 1;
#else
#pragma message "Falling back to iterative bitscan forward, consider using intrinsics"
        if (source != 0)
        {
            for (int32_t i = 0; i < 32; i++)
            {
                if (source & (1u << i))
                {
                    return i;
                }
            }
        }
        return -1;
#endif
    }

    int32_t bitScanReverse(uint32_t source)
    {